A negative multiparametric magnetic resonance imaging finding does not guarantee the absence of significant cancer among biopsy-proven prostate cancer patients: a real-life clinical experience

'Stealth' Prostate Tumors

BACKGROUND

The aim of this study was to determine the false negative rates of prebiopsy magnetic resonance imaging (MRI) and MRI-ultrasound (US) 12-core systematic prostate biopsy (PBx) by analyzing radical prostatectomy specimens.

METHODS

This retrospective study included 3600 prostate cancer (PCa) patients who underwent robot-assisted laparoscopic radical prostatectomy. Based on comparison of lobe-specific data on final pathology with preoperative biopsy and imaging data, the study population was subdivided into group I-contralateral (CL) benign PBx (n = 983), group II-CL and/or bilateral (BL) non-suspicious mpMRI (n = 2223) and group III-CL benign PBx + non-suspicious mpMRI (n = 688). This population was studied for the presence of PCa, clinically significant PCa (csPCa), extracapsular extension (ECE) (pathological stage pT3), positive frozen section and final positive surgical margin (PSM) in the CL lobe. Descriptive statistics were performed.

RESULTS

In subgroups I, II and III, PCa was respectively detected in 21.5%, 37.7% and 19.5% of cases, and csPCa in 11.3%, 16.3% and 10.3% of cases. CL pT3 disease was seen in 4.5%, 4% and 5.5%, and CL surgical margins and/or frozen section analysis were positive in 6%, 7% and 5% of cases in subgroups I, II and III, respectively.

CONCLUSIONS

There are still significant rates of false negatives in the standard care diagnostics of PCa. Further strategies are required to improve the accuracy of diagnosis and determination of tumor location.

Identifying Risk Factors for MRI-Invisible Prostate Cancer in Patients Undergoing Transperineal Saturation Biopsy

Purpose

Prostatic multi-parametric magnetic resonance imaging (mpMRI) has markedly improved the assessment of men with suspected prostate cancer (PCa). Nevertheless, as mpMRI exhibits a high negative predictive value, a negative MRI may represent a diagnostic dilemma. The aim of this study was to evaluate the incidence of positive transperineal saturation biopsy in men who have negative mpMRI and to analyse the factors associated with positive biopsy in this scenario.

Patients and Methods

A retrospective study of men with normal mpMRI and suspicion of PCa who underwent saturation biopsy (≥20 cores) was carried out. A total of 580 patients underwent transperineal MRI/transrectal ultrasound fusion targeted biopsies or saturation prostate biopsies from January 2017 to September 2020. Of them, 73 had a pre-biopsy negative mpMRI (with Prostate Imaging – Reporting and Data System, PI-RADS, ≤2) and were included in this study. Demographics, clinical characteristics, data regarding biopsy results and potential predictive factors of positive saturation biopsy were collected. Univariate and multivariate logistic regression analyses were used to identify independent risk factors for MRI-invisible PCa.

Results

The detection rate of PCa with saturation biopsy in patients with negative MRI was 34/73 (46.58%). Out of 34 MRI-invisible prostate cancers detected, 12 (35.29%) were clinically significant PCa (csPCa) forms. Regarding factors of positive biopsy, in univariate analysis, the use of 5-alpha reductase inhibitors and free:total prostate-specific antigen (PSA) ratio were associated with the result of the saturation biopsy. In multivariate analysis, only an unfavourable free:total PSA ratio remained a risk factor (OR 11.03, CI95% 1.93–63.15, p=0.01). Furthermore, multivariate logistic analysis demonstrated that prostate volume >50mL significantly predicts the absence of csPCa on saturation biopsy (OR 0.11, 95% CI 0.01–0.94, p=0.04).

Conclusion

A free:total PSA ratio <20% is a risk factor for MRI-invisible PCa. Saturation biopsy could be considered in patients with suspected PCa, despite having a negative MRI.

The diagnostic accuracy of multiparametric MRI for detection and localization of prostate cancer depends on the affected region

Objectives

To determine the diagnostic accuracy of 3T multiparametric magnetic resonance imaging (mpMRI) for detecting and locating prostate cancer (PCa) on Dickinson's 27‐sector map, using histopathology specimens from radical prostatectomy (RP) as the reference standard.

Patients and methods

The authors studied a continuous series of 140 patients who underwent RP over three consecutive years. Prior to RP, all patients had mpMRI for detection and localization of PCa and further assessment by biopsy. To minimize the potential of disease progression, 25 patients were excluded because the interval between mpMRI and RP exceeded 6 months, which left 115 patients eligible for analysis. The mpMRI findings were reported using the Prostate Imaging‐Reporting and Data System (PI‐RADS) v2, considering PI‐RADS ≥ 3 to indicate PCa. The histopathology findings from RP specimens were graded using the Gleason scoring system, considering Gleason ≥ 6 to indicate PCa. The location of the tumors was mapped on Dickinson's 27‐sector map for both mpMRI and histopathology and compared by rigid sector‐by‐sector matching.

Results

The cohort of 115 patients eligible for analysis was aged 66.5 ± 6.0 years at RP. Of the 3105 sectors analyzed, there were 412 true positives (13%), 28 false positives (1%), 68 false negatives (2%), and 2597 true negatives (84%). Across the 27 sectors of the prostate, mpMRI sensitivity ranged from 50% to 100% and specificity from 96% to 100%, while PPV ranged from 50% to 100%, and NPV from 91% to 100%. For the anterior prostate, mpMRI had a sensitivity of 80% (CI, 71%‐86%), specificity of 99% (CI, 99%‐100%), PPV of 91% (CI, 83%‐95%), and NPV of 99% (CI, 98%‐99%). For the posterior prostate, mpMRI had a sensitivity of 88% (CI, 84%‐91%), specificity of 98% (CI, 97%‐99%), PPV of 94% (CI, 92%‐96%), and NPV of 96% (CI, 94%‐97%). Overall, mpMRI had a sensitivity of 86%, specificity of 99%, PPV of 94%, and NPV of 97%.

Conclusions

The accuracy of mpMRI in detecting and locating prostate tumors depends on the affected region, but its high NPV across all sectors suggests that negative findings may not need corroboration by other techniques.

Tracking Changes in Clinical Practice Patterns Following Prebiopsy Biparametric Prostate MRI

RATIONALE AND OBJECTIVES

To evaluate the change in clinical practice after implementation of prebiopsy biparametric MRI followed by targeted biopsy and the benefits of prebiopsy MRI based on real clinical practice.

MATERIALS AND METHODS

A total of 1,661 patients who underwent either transrectal biopsy or prebiopsy MRI for suspected prostate cancer between October 2015 and March 2018 were enrolled in this retrospective single-center study. To evaluate temporal changes in clinical practice, the study time was divided into five periods of six months. Prebiopsy prostate MRI was officially started in April 2016 in this center. Differences in practice patterns were compared among the five periods, and differences in biopsy results were compared in three groups: no prebiopsy MRI, negative MRI and positive MRI.

RESULTS

Prostate cancers were diagnosed in 463 patients. The proportion of patients who underwent prebiopsy MRI regardless of biopsy increased from 22.6% in period 1 to 84.4% in period 5 (P < 0.001). The proportion of patients who avoided biopsy according to MRI results increased significantly from 9.0% in period 1 to 48.1% in period 5 (P < 0.001). The prostate cancer detection rate and the number of positive cores were lower in the negative MRI group than those in the positive MRI and no prebiopsy MRI groups.

CONCLUSION

Prebiopsy MRI using biparametric MRI protocol has been well adapted to the practice and it is useful in stratifying the probability of clinically significant prostate cancer.

Role of multiparametric magnetic resonance imaging to predict postoperative Gleason score upgrading in prostate cancer with Gleason score 3 + 4

BACKGROUND

To evaluate the role of multiparametric magnetic resonance imaging (mpMRI) in Gleason score (GS) 3 + 4 prostate cancer (PCa) and evaluate independent factors in mpMRI that can predict GS upgrading, we compared the outcomes of GS upgrading group and GS non-upgrading group.

PATIENTS AND METHODS

We analyzed the data of 539 patients undergoing radical prostatectomy (RP) for biopsy GS 3 + 4 PCa from two tertiary referral centers. Univariate and multivariate analyses were performed to determine significant predictors of GS upgrading. GS upgrading, the study outcome, was defined as GS ≥ 4 + 3 at definitive pathology at RP specimen.

RESULTS

GS upgrading rate was 35.3% and biochemical recurrence (BCR) rate was 8.0%. GS upgrading group was significantly older (p = 0.015), had significantly higher prebiopsy serum prostate-specific antigen (PSA) level (p = 0.001) and PSA density (p = 0.003), had a higher number of prostate biopsy (p = 0.026). There were 413 lesions (76.6%) of PI-RADS lesion ≥ 4, 236 (57.1%) for PI-RADS 4 and 177 (42.9%) for PI-RADS 5 lesion. Multivariate logistic regression analysis revealed that age (p = 0.045), initial prebiopsy PSA level (p = 0.002) and presence of PI-RADS lesion ≥ 4 (p = 0.044) are independent predictors of GS upgrading.

CONCLUSION

MpMRI can predict postoperative Gleason score upgrading in prostate cancer with Gleason score 3 + 4. Especially, presence of clinically significant PI-RADS lesion ≥ 4, the significant predictor of GS upgrading, in preoperative mpMRI needs to be paid attention and can be helpful for patient counseling on prostate cancer treatment.

Role of Multiparametric Magnetic Resonance Imaging in Predicting Pathologic Outcomes in Prostate Cancer

Multiparametric magnetic resonance imaging (mpMRI) and the introduction of standardized protocols for its interpretation have had a significant impact on the field of prostate cancer (PC). Multiple randomized controlled trials have shown that the sensitivity for detection of clinically significant PC is increased when mpMRI results are the basis for indication of a prostate biopsy. The added value with regards to sensitivity has been strongest for patients with persistent suspicion for PC after a prior negative biopsy. Although enhanced sensitivity of mpMRI is convincing, studies that have compared mpMRI with prostatectomy specimens prepared by whole-mount section analysis have shown a significant number of lesions that were not detected by mpMRI. In this context, the importance of an additional systematic biopsy (SB) is still being debated. While SB in combination with targeted biopsies leads to an increased detection rate, most of the tumors detected by SB only are considered clinically insignificant. Currently, multiple risk calculation tools are being developed that include not only clinical parameters but mpMRI results in addition to clinical parameters in order to improve risk stratification for PC, such as the Partin tables. In summary, mpMRI of the prostate has become a standard procedure recommended by multiple important guidelines for the diagnostic work-up of patients with suspicion of PC.

Effects of "real life" prostate MRI inter-observer variability on total needle samples and indication for biopsy

PURPOSE

Prostate multiparametric magnetic resonance imaging (mpMRI) improves diagnosis of clinically significant cancer and reduces over-detection of nonsignificant cancer. Disagreement in the interpretation of mpMRI readings is well-known, with a reported discrepancy rate of 10% to 42%. We report the clinical repercussions of this variability on prostate biopsy candidates.

MATERIALS AND METHODS

Medical records of patients referred from 11 medical centers for MR-guided prostate biopsy (MRGpB) between October, 2017 and January, 2019 were retrospectively analyzed. Patients with at least one prostate imaging reporting and data system (PI-RADS) 3 or greater prostate lesion were selected, and the mpMRI studies (all read by others) were reviewed by our prostate mpMRI reader. Outcomes included changes in PI-RADS score and the subsequent effect on total needle samples and indication for biopsy.

RESULTS

Eighty-two patients with 128 lesions were suitable for analysis (mean age 66.5 ± 7.1 years, mean PSA 6.8 ± 8.5 ng/ml). Nine (11%) patients had suspicious rectal exams (T2a). Following our prostate mpMRI reader's imaging revisions, the PI-RADS score was downgraded in 66 (52%) lesions, upgraded in 15 (12%), and unchanged in 47 (37%), leaving a total of 84 suspected lesions (kappa = 0.17). Biopsy was deferred in 22 (27%) patients, and an estimated 136.4 (34.4%) samples were avoided (P = 0.0001 for both). There was a trend toward prostate size to correlate with imaging revision and abortion of biopsy (P = 0.06) while enrollment in active surveillance correlated with proof from such outcome (P = 0.007).

CONCLUSION

These data suggest that high interobserver disagreement in prostate mpMRIs from diverse institutes significantly affects prostate biopsy practice. The clinical consequences of this discord are significant.